Two England supporters were arrested Wednesday in Porto's city centre after clashing with Portuguese fans watching the Nations League semi-final against Switzerland, according to police.
"There was a scuffle between English and Portuguese supporters, with bottles thrown, and the police had to intervene," Portuguese police spokesman Alexandre Coimbra told AFP.
"The English supporters turned against the police who arrested two of them and identified a third," he said.
Video on social networks showed police holding batons and riot shields breaking up dozens of supporters in a fan zone in Porto.
Portugal qualified for Sunday's final after a hat-trick by Cristiano Ronaldo gave them a 3-1 win over Switzerland. England play the Netherlands in the second semi-final on Thursday in Guimaraes.